Upgrading and Repairing PCs

Interfaces for Removable Media Drives

In addition to choosing a type of device, you must choose which type of interface is ideally suited for connecting it to your PC. Several connection options are available for the leading removable drives. The most common interface (and one of the fastest) for internally mounted drives is the same AT Attachment (ATA) interface used for most hard drives. SCSI interfacing is as fast or even faster for use with either internal or external drives but requires adding an interface card to most systems. Most high-end tape backups require a SCSI interface.

The most common external interface is now the USB port, which has largely replaced the venerable parallel port for printing as well as for interfacing low-cost external drives and other types of I/O devices. The USB port is available on virtually all recent PCs (both desktop and notebook models); can be hot-swapped; and is supported by Windows 98 and later, including Windows Me, Windows 2000, and Windows XP. For small-capacity (under 300MB) removable-media devices, the performance of USB 1.1 (12Mbps) is adequate, but larger removable-media devices should be connected to the faster USB 2.0 port (480Mbps) or the 400Mbps IEEE-1394a (FireWire/i.Link) port if possible. Most flash memory devices must be connected to a card reader, which usually plugs into a USB port. Older interfaces such as the parallel port and PC Card (for notebook computers) are still used on some devices but have limited performance. These are recommended only for systems that don't support USB (such as those still running Windows 95 or Windows NT). Some external removable-media drives allow you to interchange interfaces to enable a single drive to work with a variety of systems.

Note Although late versions of Windows 95 ("Win95C" or OSR2.1 and above) also have USB drivers, many developers of USB devices do not support their use with Windows 95. For reliable results and manufacturer support, use Windows 98, Windows Me, Windows 2000, or Windows XP.

As you will see in the following sections, most removable-media drives are available in two or more of these interface types, allowing you to choose the best interface option for your needs.

Note Connecting or installing removable-media drives is similar to connecting and installing other internal and external peripherals. The external USB, IEEE-1394, or parallel port drives are the simplest of the available interfaces, requiring only a special cable that comes with the drive and installation of special software drivers. See the instructions that come with each drive for the specifics of its installation. See Chapter 7, "The ATA/IDE Interface"; Chapter 8, "The SCSI Interface"; and Chapter 17, "I/O Interfaces from Serial and Parallel to IEEE-1394 and USB," for details on how these interfaces operate.